• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.05b
• /
• pp.3-6
• /
• 2004

In this paper, we studied on permissible current of unperfected earthing for cross-bond system. The factors of unperfected earth were jacket damage, cross-bonding mistake, arrestor damage, effect of other circuit but we only studied permissible current of arrestor or jacket damage. In the result, we earned that permissible current of normal 154[[kV]] CV $1C{\times}400SQMM$ cable is 760[A] but current of unperfected earthing cable is 76[A], unperfected earthing confirmed that accident of underground cable could occur. So, we could confirmed that Earthing resistance of unperfected earthing need to limit.

• Proceedings of the KIEE Conference
• /
• 2001.04a
• /
• pp.401-403
• /
• 2001

This paper presents an advanced calculation method of permissible current capacity on catenary system. If the permissible current calculation method used in electric power system is applied to electric railroad system, it is troublesome. Because electric load in catenary system varies periodically according to time. Therefore, this study proposes permissible current calculation method through heat equation according to time variation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.30 no.3
• /
• pp.53-58
• /
• 2016

The underground transmission lines which have been built to expand the suppling facilities will be continuously accompanying with high growth of the increase of power demand in the metropolitan area in recent years. So, it is necessary to maximize the ability and reliability of power supply with the current-carrying capability of the underground transmission lines. Design criteria of KEPCO is to be presented and used frequently. But it has to be studied about the installation methods of power cable buried in ground. In this study, we used the program for calculating the current-carrying capability of underground transmission power cables. We estimated the maximum permissible current values by the horizontal arrangement in the installation methods of power cable(154kV XLPE $600mm^2$) buried ducts in ground. To see the general tendency of the analysis, we researched a statistical analysis with such parameters as the maximum permissible current values. Through the regression analysis, we analyze the most highly values of the maximum permissible current on the Ra type duct arrangement.

• Journal of Magnetics
• /
• v.20 no.4
• /
• pp.450-459
• /
• 2015

In this paper, the safety distances and maximum permissible power (MPP) of resonant wireless power transfer systems are defined and derived with regard to human exposure to electromagnetic field (EMF). The definition is based on the calculated induced current density and electric field in the standard human model located between the transmitting and receiving coil. In order to avoid the adverse health effects such as stimulation of nerve tissues, the induced current and electric field must not exceed the basic restriction values specified in EMF safety guidelines. The different combinations of diameters of the coils and the distance between the two coils are investigated and their effects are analyzed. Two versions of EMF safety guidelines (ICNIRP 1998 and ICNIRP 2010) are used as bases for safety distance calculation and the difference between the two guidelines are discussed.

• Proceedings of the KIEE Conference
• /
• 1990.07a
• /
• pp.304-307
• /
• 1990

Referring to the calculation of the continuous permissible current rating in 22.9kV CN/CV underground distribution power cables, the current and temperature have been fully discussed and analyzed based on their three different values: one is the actually measured value throughout our test and the other two are calculated in connection with different specifications IEC-287 and JCS-168-D respectively. For this purpose, our test has been carried out with real cables which have been under stress either with induced current or with rating voltage. In the former, the calculated current of IEC-287 shows closer value to the measured one than that of JCS-168-D does. In the latter, there has been little difference on the temperature comparing with that measured without voltage application. Therefore, we think that it is preferable to choose the IEC-287 specification for the calculation of the continuous permissible current rating in the commercially power cables.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.6
• /
• pp.19-27
• /
• 2015

Permissible soil concentrations for explosives (i.e., TNT and RDX) and heavy metals (i.e., Cu, Zn, Pb, and As) heve been derived from human risk and ecotoxicity, respectively. For TNT and RDX, human risk based-permissible soil concentrations were determined as 460 mg-TNT/kg-soil and 260 mg-RDX/kg-soil. Ecotoxicity based-permissible soil concentrations for Cu and Zn were determined from species sensitivity distribution (SSD) and uncertainty factor of 1 to 5, yielding 18.0-40.0 mg-Cu/kg-soil and 46.0-100 mg-Zn/kg-soil. For Pb and As, ecotoxicity data were not enough to establish SSD so that a deterministic method was used, generating 13.8-30.8 mg-Pb/kg-soil and 2.10-4.60 mg-As/kg-soil. It is worth noting that the methodology used to derive permissible concentrations in soil can differ depending on ecotoxicity data availability and socio-economic situations, which results in different permissible concentrations. The permissible concentrations presented in this study have been derived from conservative assumptions for exposure parameters, and thus should be considered as soil standards. In the light of remediation and pollution management of a site of interest, the site-specific and receptor-specific permissible soil concentrations should be derived considering potential receptors, current and future land use, background concentrations, and socio-economic consultation.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.256-258
• /
• 2002

This paper analyzes the sensitivity of the permissible current-carrying capability of underground power cables according to the thermal property of backfill materials and construction size of backfill materials. It is helpful for operators to determine the operating current and to design the construction of underground power cables.

• Steel and Composite Structures
• /
• v.26 no.1
• /
• pp.45-53
• /
• 2018

Experimental investigations have revealed significant mismatches between analytical estimates and experimentally measured deflections of transmission towers. These are attributed to bolt slip and joint flexibility. This study focuses on effects of joint flexibility on tower deflections and proposes criterions for permissible deflection limits based on the stresses in joints. The objective has been framed given that guidelines are not available in the codes of practices for transmission towers with regard to the permissible limits of deflection. The analysis procedure is geometric and material nonlinear with consideration of joint flexibility in the form of extension or contraction of the cover plates. The deflections due to bolt slip are included in the study by scaling up the deflections obtained from analysis by a factor. Using the results of the analysis, deflection limits for the towers are proposed by limiting the stresses in the joints. The obtained limits are then applied to a new full scale tower to demonstrate the application of the current study.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.25 no.2
• /
• pp.134-145
• /
• 2015

Objectives: An objective of this study was to perform a risk assessment and social cost-benefit analysis for revising permissible exposure limits for seven substances: Nickel(Insoluble inorganic compounds), benzene, carbon disulfide, formaldehyde, cadmium(as compounds), trichloroethylene, touluene-2,4-diisocyanate. Materials and Methods: The research methods were divided into risk and hazard assessment and cost-benefit analysis. The risk and hazard assessment for the seven substances consists of four steps: An overview of GHS MSDS(1st), review of document of ACGIH's TLVs (2nd), comparison between international occupational exposure limits and domestic permissible exposure limits(3rd), and analysis of excess workplace and excess rate for occupational exposure limits based on previous work environment measurement data(4th). Total cost was estimated using cost of local exhaust ventilation, number of excess workplace and penalties for exceeding a permissible exposure limit. On the other hand, total benefit was calculated using the reduction rate of occupational disease, number of workplaces treating each substance and industrial accident compensation. Finally, the net benefit was calculated by subtracting total cost from total benefit. Results: All the substances investigated in this study were classified by CMR(Carcinogens, Mutagens or Reproductive toxicants) and their international occupational exposure limits were stricter than the domestic permissible exposure limits. As a result of excess rate analysis, trichloroethylene was the highest at 11%, whereas nickel was the lowest at 0.5%. The excess rates of all substances except for trichloroethylene were observed at less than 10%. Among the seven substances, the total cost was highest for trichloroethylene and lowest for carbon disulfide. The benefits for the seven substances were higher than costs estimated based on strengthening current permissible exposure limits. Thus, revising the permissible exposure limits of the seven substances was determined to be acceptable from a social perspective. Conclusions: The final revised permissible exposure limits suggested for the seven substances are as follows: $0.2mg/m^3$ for nickel, 0.5 ppm(TWA) and 2.5 ppm(STEL) for benzene, 1 ppm(TWA) for carbon disulfide, $0.01mg/m^3$(TWA) for cadmium, 10 ppm(TWA) and 25 ppm(STEL) for trichloroethylene, 0.3 ppm(TWA) for formaldehyde, and 0.005 ppm(TWA) and 0.02 ppm(STEL) for toluene diisocynate(isomers).

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.467-469
• /
• 2004

When power cables cross regions with unfavorable thermal conditions, conductor temperatures higher than the design value can occur. This paper proposes the calculation algorithms of the permissible current-carrying capability using the algorithm of calculating the longitudinal conductor temperature distribution of power cables installed in thermally dissimilar soil materials.